Abstract

The chemical bonding and electronic properties of wet, chemically treatedsurfaces were studied using synchrotron radiation photoemission spectroscopy. Chlorine-based chemical bonding was identified on the conventional HCl-treated surface, which is associated with a shift of the surfaceFermi level toward the conduction band edge by ∼0.9 eV with respect to the thermally cleanedsurface. Compared to the HCl-treated surface, the surfaceFermi level on the KOH-treated surface lies about ∼1.0 eV closer to the valence band edge, resulting in a much smaller surface barrier height to p-type materials than the HCl-treated surface. The smaller surface barrier height to after KOH treatment can lead to a lower contact resistivity and can play an important role in lowering the metal contact resistivity to